Method matchNext

src/time/matcher-walker.ts:53–82

* Finds the next instant that satisfies the expression, strictly after the * base date. * * Instead of scanning time tick by tick, it infers candidates directly from * the cron fields: it walks the calendar day by day (a Y/M/D is the same * weekday in every timezone), and on each day

()

   * non-existent local times (the DST spring-forward gap) by construction.
   */
  matchNext(): LocalizedTime {
    const months = this.months;
    const days = this.days;

    const baseMs = Math.floor(this.baseDate.getTime() / 1000) * 1000;
    const baseParts = new LocalizedTime(new Date(baseMs), this.timezone).getParts();

    let { year, month, day } = baseParts;

    for (let i = 0; i < MAX_DAYS; i++) {
      // Pre-check month, day-of-month and weekday before the (potentially
      // 86,400-wide) time-of-day scan. The weekday check mirrors match()
      // exactly, so it only skips days that would be rejected anyway, and it
      // avoids scanning every time on a day whose weekday can't match (e.g.
      // `* * * 15 * 1`, the 15th only when it is a Monday).
      if (months.includes(month) && matchesDayOfMonth(days, year, month, day) && this.matchesWeekday(year, month, day)) {
        // On the base day the result must be strictly after the base instant;
        // on later days any matching time of day qualifies.
        const lowerBound = i === 0 ? baseParts : null;
        const found = this.firstTimeOnDay(year, month, day, lowerBound, baseMs);
        if (found !== null) {
          return new LocalizedTime(new Date(found), this.timezone);
        }
      }

      ({ year, month, day } = nextDay(year, month, day));
    }

    throw new Error('Could not find next matching date within reasonable time range');
  }

  /**
   * Smallest matching (hour, minute, second) on the given calendar day that